How Zika spreads (and who’s to blame)
Zika is no longer a global health emergency spreading across borders and requiring a coordinated international response, the World Health Organization declared on Friday, while emphasizing that managing the infectious disease remains a significant challenge for the long-term.
The WHO declaration does not mean that people should stop taking steps to prevent the spread of Zika, which is transmitted primarily by the bite of an infected Aedes aegypti species of mosquito but also through sex, said Dan Epstein, a spokesman for the international health agency.
“Zika is still a very significant long-term problem,” Epstein said, noting that the WHO’s declaration has no influence on efforts by Miami-Dade, Florida and the Centers for Disease Control and Prevention to combat spread of the virus by spraying pesticides, trapping mosquitoes and other approaches.
“We certainly collaborate with them,” he said, “but we’re not involved operationally.”
WHO officials first declared Zika a Public Health Emergency of International Concern in February after an outbreak of the virus in Brazil led to a cluster of birth defects and other neurological disorders in babies born to mothers infected while pregnant.
Since then, Zika has spread through the Caribbean, Central America, nearly all of South America and other parts of the world. Researchers also have learned more about the virus, including identifying a causal link between Zika and microcephaly — though even that connection requires more research, Epstein said.
“There’s a lot of work to do, and what we have to do is improve and coordinate more research,” he said. “We don’t know in some cases whether populations that live in countries where Zika is now endemic are already immune to infection. … We don’t know what co-factors are causing more microcephaly cases in some areas than others.”
Zika is still a very significant long-term problem.
Dan Epstein, World Health Organization spokesman
Mara Gambineri, a spokeswoman for the Florida Department of Health, said the state still considers Zika a public health threat.
“Our state continues to see increases in both travel-related and locally acquired cases of Zika,” she said. “Everyone, especially pregnant women, still need to take Zika seriously and remain vigilant.”
In Florida, health officials have reported 1,188 Zika infections this year, with 234 locally acquired cases and 939 travel-related cases. Included in those two categories are 160 pregnant women, but the health department does not disclose their counties of residence or manner of infection.
Miami-Dade remains the only county in Florida with active mosquito-borne spread of Zika, with four new locally acquired cases reported on Friday.
A total of 38 Florida counties are under a state public health emergency declaration because of Zika, though all but four counties have reported only travel-related cases acquired abroad in areas where the virus is widespread. Locally transmitted Zika infections have been reported in Broward, Miami-Dade, Palm Beach and Pinellas counties — but active spread of the virus has been identified only in sections of Miami and Miami Beach.
Of the 234 mosquito-borne Zika infections statewide confirmed by the health department this year, 222 cases were contracted in Miami-Dade.
222 Locally acquired Zika infections in Miami-Dade this year
Among the Miami-Dade cases, 38 were exposed in Miami’s Wynwood district, 77 in Miami Beach, 10 in Miami’s Little River neighborhood, and 93 somewhere within the county but outside of those designated zones. Another four mosquito-borne cases in Miami-Dade had possible exposure in Miami Beach and Wynwood.
As of Friday, the state health department was conducting 10 investigations in Miami-Dade, including one each in a one-square-mile section of Little River and a 4.5-square-mile zone in Miami Beach. The remaining eight investigations in Miami-Dade are outside of those two zones.
Gambineri said the department has seen a rise in Miami-Dade infections requiring investigation to determine the area of exposure because the agency is now announcing cases once it receives lab confirmation of Zika — rather than waiting for epidemiologists to complete their probe into where transmission occurred.
The health department also is seeing more infections involving people who have traveled to Miami Beach, Little River and elsewhere in the county, increasing the difficulty for epidemiologists to pinpoint the area of exposure, she said.
“For some we may never determine exactly where transmission occurred,” Gambineri said, “but … the primary purpose of an investigation is to determine if additional people are infected and if active transmission of Zika is occurring in an area.”
Zika cases in Florida as of Nov. 18
Number of Cases
Total travel-related cases
Total locally acquired infections
* Counties of pregnant women not identified, number includes locally acquired and travel-related infections reported in totals
** Does not include local cases
Source: Florida Department of Health